A synthesis gas containing hydrogen and carbon monoxide is used as a raw material for the synthesis of F-T, methanol, ammonia, or the like.
The synthesis gas is prepared from various organic compounds. It is known that a method for preparing the synthesis gas is a reaction of the organic compound with steam and/or carbon dioxide, a partial oxidation of the organic compound by oxygen and/or air, etc.
In particular, with regard to a gaseous organic compound, the following methods are used: (1) a method of reacting an organic compound with steam and/or carbon dioxide at high temperatures in the presence of a catalyst, (2) a method comprising a partial oxidization of an organic compound with oxygen and/or air to generate heat, with which steam and/or carbon dioxide is/are mixed and reacted in a catalyst layer, and (3) a combination of (1) and (2).
However, the above methods have disadvantages as follows.
In the (1) method, since carbon is produced on a catalyst by decomposing an organic compound at high temperatures, an upper limit of the temperature is given. In the (2) method, an organic compound is rapidly decomposed by oxygen, but the organic compound as a heat source is preferably consumed as little as possible. Therefore, the method preferably requires a low temperature. Further, since in any method of (1) to (3), a reaction which produces carbon on a catalyst from a produced carbon monoxide may also occur, a lower limit of the temperature is given.
In order to solve these problems, the following methods have been disclosed.
As a method for preparing a synthesis gas using a catalyst, for example, Patent Document 1 discloses a process in which a catalyst having suppressed carbon deposition activity is used for the reaction of the unreacted carbon-containing organic compound in the high-temperature mixed gas with carbon dioxide and/or steam. Patent Document 2 discloses a process wherein, with an object of providing a catalyst for production of a synthesis gas by a methane reforming reaction, a high activity catalyst for methane reforming can be obtained by modifying the catalyst by supporting on a carrier or by mixing to the catalyst a specific amount of at least one metal compound selected from platinum group metal elements.
On the other hand, for a method for preparing synthesis gas without a catalyst, Patent Document 3 discloses that the formation temperature is set to about 1000 to 1900° C.
[Patent Document 1]
PCT Japanese Translation Patent Re-Publication No. WO98/46525
[Patent Document 2]
Japanese Unexamined Patent Application Publication No. 9-131533
[Patent Document 3]
Japanese Examined Patent Application Publication No. 52-46192